Interpretation ID: aiam0828
Manager
Safety & Development
Volkswagen of America
Inc.
Englewood Cliffs
NJ
07632;
Dear Mr. Kennebeck: This is in reply to your letter of July 27, 1972, requesting a interpretation of S4.3 of Motor Vehicle Safety Standard No. 302, 'Flammability of Interior Materials', and an opinion regarding the applicability of Standard No. 302 to your Model 15 convertible top cover.; You ask whether the basic burn rate of not more than 4 inches pe minute or the burn rate of 2 inches in less than 60 seconds should be applied to material which self-extinguishes after 55 seconds at a burn distance of 3 inches. The answer to this question is that the basic burn rate of not more than 4 inches per minute applies to this case. The basic burn rate requirement, calculated according to the formula given in S5.3(g), applies whenever the tested material burns more than 2 inches or more than 60 seconds. This 2-inch, 60-second burn rate provided in the second sentence of paragraph S4.3 is given to simplify the calculation of certain self-extinguishing materials, not for the purpose of imposing an additional requirement.; In regard to your graphic illustrations and you request for our opinio with respect to the validity of your Figure 3, you are correct in assuming that materials falling under the B-line are acceptable and that the portions of the shaded area under the B-line in Figure 2 represent an overlap that is in the acceptable area. The second burn rate was intended as a means for rapid qualification of test specimens that, because of their specified flammability limits, would be acceptable without further calculation to determine the burn rate. Any materials falling outside of the 2-inch or 60-second limits require calculation. It would, as you suggest, be a further simplification to say that material that self-extinguishes before burning 2 inches meets the performance requirement and is acceptable.; You ask further whether Standard No. 302 applies to your Model 1 convertible top cover. We consider for this purpose a convertible top cover, or boot, to be part of the convertible top itself and consequently subject to the standard.; Yours truly, Richard B. Dyson, Assistant Chief Counsel